text: Bussard Ramjets are common plot devices in science fiction.
  Larry Niven uses them in his Known Space setting to propel interstellar flight.  Following a standard hi-tech faster/cheaper/better learning curve, he started with robot probes during the early stages of interstellar colonization and eventually plotted them as affordable to wealthy individuals relocating their families off a too-crowded Earth (in "The Ethics of Madness").  Niven also employed Bussard Ramjets as the propulsion / stabilizing engine of the Ringworld (four novels), which were also set in Known Space.
  In the Star Trek universe, a variation called the Bussard Hydrogen Collector or Bussard Ramscoop appears as part of the matter/antimatter propulsion system that allows Starfleet ships to travel faster than the speed of light. The ramscoops attach to the front of the warp nacelles, and when the ships internal supply of deuterium runs low, they collect interstellar hydrogen and convert it to deuterium and anti-deuterium for use as the primary fuel in a starships warp drive.